US 6,284,167 B1 · Method and apparatus for purging leaked resin in a preplasticization injection molding machine

Abstract

When a process measurement metering operation is performed during a molding cycle, a plunger is forcibly caused to retract to a position behind measurement metering completed position, while at the same time a periodic forced purge operation is implemented in which the plunger is immediately restored to the vicinity of the position at which the forced retraction operation commenced. By this operation, leaked resin is removed to the rear, i.e., beyond the plunger metering stroke range, and any increase in resistance to movement of the plunger due to disposition of leaked resin is avoided. The forced purge operation is preferably performed either immediately prior to the normal metering operation, or after a specified time has elapsed following completion of a metering operation.

Claims36

Dependent claims

A method of purging leaked resin in a preplasticizing injection molding machine having an injection device including an injection plunger having a head portion and a shaft portion, the head portion having a larger diameter than the shaft portion, said method including a metering operation and further comprising the steps of:

forcibly retracting the injection plunger to a forced retraction position which is a pre-determined position that exceeds the metering completed position;
forcibly restoring the injection plunger to a position at or slightly displaced from said metering completed position;
said forcibly retracting and forcibly restoring steps being performed periodically with respect to said metering operation;
wherein said forced retraction position is a position representing an increased retraction position from any suck back position to which the plunger may retract beyond the metering completed position.

1 more element

A method of injection molding using a preplasticizing injection molding machine, said preplasticizing injection molding machine having an injection unit, a preplasticizing unit, a connection path between said injection unit and preplasticizing unit, and a valving device in the connecting path for isolating the injection unit from the preplasticizing unit, and wherein the injection unit includes an injection plunger having a head portion, a shaft portion and a chamber in which said injection plunger is disposed to reciprocate, and the plunger head portion being larger in diameter than the shaft portion thereof and the injection chamber having a purge hole proximate an end thereof in which said shaft portion is disposed, said method comprising;

(a) an injection operation comprising the steps of;
(1) melting plastic resin in the preplasticizing chamber;
and
(2) metering the plastic resin in said injection chamber with the molten resin introduced from the preplasticizing chamber into the injection chamber via said connection path;
(3) isolating the injection chamber from the preplasticizing chamber;
(4) injecting plastic resin as the injection plunger advances in the injection chamber, and
(b) periodically purging through the purge hole any plastic resin which has leaked behind the head portion of the injection plunger, said step of periodically purging further comprising:
(1) forcibly retracting the injection plunger from a retraction start position to a predetermined position which exceeds a metering completed position of said injection plunger, without performing said melting and metering steps;
and
(2) forcibly restoring the injection plunger to a position at or slightly behind said forced retraction start position, without performing an injection operation.

7 more elements

A leaked resin purge control device for a preplasticizing injection molding machine having an injection device including an injection plunger disposed in an injection chamber, said injection plunger comprising a head portion and a shaft portion, said head portion having a larger diameter then the shaft portion, said control device including a leaked resin purge control comprising:

an injection plunger drive for controlling the movement of the injection plunger;
a position detector for detecting the position of the injection plunger, and
a drive-control for controlling the injection plunger drive, said drive-control further comprising a main control device operable, immediately prior to the start of a metering operation, to determine the position of said injection plunger, to force purge from said injection chamber any resin behind said injection plunger head portion and adjacent said shaft portion by forcibly retracting the injection plunger to a preset position in said injection chamber beyond a metering completed position reached during said metering operation, and then forcibly restoring the injection plunger to a position at or behind a forced retraction start position at which the forced retraction commenced.

A resin purging control device for a preplasticizing injection molding machine having an injection device including an injection plunger having a head portion and a shaft portion, said head portion having a larger diameter than said shaft portion, and a resin purging control device, and further comprising;

an injection plunger drive for controlling the movement of the injection plunger;
a position detector for detecting the position of the injection plunger;
and a drive-control for controlling the injection plunger drive;
and
said resin purging control device further comprising a main control device, operable during a specified time interval following the completion of a metering operation to determine the position of said injection plunger to execute a forced purge operation comprising forcibly retracting the injection plunger to a preset position beyond the metering completed position at which said metering operation is completed, and a forced restoring operation to forcibly restore the position of the injection plunger to a position at or behind the forced retraction start position at which forced retraction commenced.

2 more elements

An apparatus for controlling an injection molding cycle of a preplasticizing type injection molding machine, said preplasticizing injection molding machine including an injection unit having an injection chamber, a preplastisticizing unit having a preplasticizing chamber, a passage for connecting the preplasticizing chamber and the injection chamber, a valving device for closing the connecting passage, wherein said injection unit further comprises an injection plunger disposed in said injection chamber for reciprocal movement therein, said injection plunger having a head portion larger in diameter than a shaft portion thereof and said injection chamber having a purge hole at an proximate end thereof wherein the shaft portion of said injection plunger is disposed, said apparatus comprising:

an input device for inputting set values for controlling an injection operation;
a display for displaying the operational state of the molding machine and of said values;
and
an injection molding controller for controlling (i) a forced purging operation for purging plastic resin which may have leaked to a location in said injection chamber where said shaft portion is disposed, and (ii) an injection operation including a resin metering operation, said forced purging operation being performed prior to said metering operation;
and
a memory operable to record:
(a) a flag identifying whether the forced purging operation is to be performed;
(b) a forced purge interval to set an interval at which the forced purging operation is to be performed
(c) a number of times the forced purging operation is suspended and the metering operation is executed;
(d) a position of the injection plunger;
(e) a forced retraction position of the injection plunger to set the retraction position of the injection plunger during a forced retraction operation and;
(f) a forced restoration position of the injection plunger to set the restore position of the injection plunger during a forced retraction operation.

9 more elements

An apparatus for controlling an injection molding cycle of a preplasticizing type injection molding machine, said preplasticizing injection molding machine including an injection unit having an injection chamber, a preplasticizing unit having a preplasticizing chamber, a passage for connecting the preplasticizing chamber and the injection chamber, a valving type and closing device for closing the connecting passage, wherein said injection unit further comprises an injection plunger disposed in said injection chamber for reciprocal movement therein, said injection plunger having a head portion larger in diameter than a shaft portion thereof and said injection chamber having a purge hole proximate an end thereof in which the shaft portion of said injection plunger is disposed, said apparatus comprising:

an input device for inputting set values for controlling an injection operation;
a display for displaying the operational state of the molding machine and of said values;
and
an injection molding controller for controlling (i) a forced purging operation for purging plastic resin which may have leaked to a location in said injection chamber where said shaft portion is disposed, and (ii) an injection operation including a resin metering operation, said forced purging operation being performed prior to said metering operation;
and
a memory operable to record:
(a) a flag identifying whether the forced purge operation is to be executed;
(b) a forced purge interval to set an interval at which the forced purging operation is to be performed;
(c) the number of times the forced purging operation is suspended and the metering step is performed;
(d) the position of the injection plunger;
(e) a metering completed position of said injection plunger;
(f) a retraction start detected position (L0), at which a forced retraction commences;
(g) a retraction increase value (dL1), based on the metering completed position, to set a position to be reached by the injection plunger during a forced retraction operation;
and
(h) a first restore increase value (dL21), based on the retraction start detected position (L0), to set a position to be reached by the injection plunger during a forced restore operation.

12 more elements

An apparatus for controlling an injection molding operation of a preplasticizing type injection molding machine, said preplasticizing type injection molding machine having an injection unit including an injection chamber, a preplasticizing unit including a preplasticizing chamber, a path between said plasticizing chamber and the injection chamber and a valving device to selectively close said path, said injection unit further including an injection plunger disposed to reciprocate in said injection chamber, said injection plunger having a head portion larger in diameter than a shaft portion thereof, and said injection chamber including a purge hole proximate an end thereof in which the shaft portion of said injection plunger is disposed, the apparatus further comprising:

an input device for inputting set values for controlling injection cycles;
a display for displaying an operational state of the molding machine operation and of said values;
and
an injection molding controller for controlling (i) a forced purging operation for purging plastic resin which may have leaked to the portion of the injection chamber where said shaft portion is disposed, and (ii) an injection molding operation which includes a plastic resin metering operation, said forced purging operation being performed after completion of said metering operation;
and wherein said injection molding controller includes a memory operable to record:
(a) a flag identifying whether the forced purging operation is to be performed;
(b) a forced purge interval to set an interval at which the forced purging operation is to be performed;
(c) the number of times the forced purging operation is suspended and the metering operation is performed;
(d) a position of the injection plunger;
(e) a forced retraction position of the injection plunger to set the position of the injection plunger during a forced retraction operation, and;
(f) a forced restoration position of the injection plunger to set the position of the injection plunger during a forced restore operation.

8 more elements

An apparatus for controlling an injection molding operation of a preplasticizing type injection molding machine, said preplasticizing type injection molding machine having an injection unit including an injection chamber, a preplasticizing unit including a preplasticizing chamber, a path between said plasticizing chamber and the injection chamber and a valving device to selectively close the path, said injection unit further including an injection plunger disposed to reciprocate in said injection chamber, said injection plunger having a head portion larger in diameter than a shaft portion thereof and said injection chamber including a purge hole proximate an end thereof in which said shaft portion is disposed, said apparatus further comprising:

an input device for inputting set values for controlling injection cycles;
a display for displaying an operational state of the molding machine operation and of said values;
and
an injection molding controller for controlling (i) a forced purging operation for purging plastic resin which may have leaked to the portion of in the injection chamber where said shaft portion is disposed, and (ii) an injection operation including a plastic resin metering operation, said forced purging operation being performed after completion of said metering operation;
said controller including a memory operable to record:
(a) a flag identifying whether the forced purging operation is to be executed;
(b) a forced purge interval to set an interval at which the forced purge is to be performed;
(c) a number of times the forced purge step is suspended and the metering operation is performed;
(d) a position of the injection plunger;
(e) a metering completed position of the injection plunger;
(f) a retraction increase value (dL1), based on the metering completed position, to set a position to be attained by the injection plunger during a forced retraction operation;
and
(g) a second restore increase value (dL22), based on the metering completed position (L), to set the position to be reached by the injection plunger during a forced restore operation.

10 more elements

Dependencies are inferred from the claim text.

Method and apparatus for purging leaked resin in a preplasticization injection molding machine

Life of this patent

Method and apparatus for purging leaked resin in a preplasticization injection molding machine

Life of this patent

Abstract

Claims36